DE2744171C2 - Electrophotographic recording material - Google Patents

Description

I.
R ₁ or χ- _R IS where mean: A a group 20th B.
ι
-C = 25th BB
ii
-CH = C-CH = -CH = CH-C-CH = CH B. -CH = CH-Ch = C-CH = CH-CH =

wherein B is an unsubstituted or substituted alkyl group having 1 to 8 carbon atoms, an unsubstituted or substituted aromatic radical, a quinoline radical, a halogen atom, a nitro group or denotes a cyano group,

R, and R ₂ , which can be the same or different, each represent an unsubstituted or substituted alkyl

■ Sjrappe with 1 to 8 carbon atoms or an allyl group,

X is an anion, and the two quinoline nuclei can contain additional substituents.

2. Electrophotographic recording material according to claim 1, characterized in that the foioieitiahige layer has a two-layer structure, consisting of a charge-generating layer and a charge-transporting layer, wherein the quinocyanine pigment represented by the general formula (I) is present in the charge-generating layer of the photoconductive layer.

3. Electrophotographic recording material according to claims 1 or 2, characterized in that that the quinocyanine pigment according to the general formula (I) has a particle size of about 5 pm or has underneath.

4. Electrophotographic recording material according to claim 1, characterized in that the photoconductive layer additionally contains an electrically insulating resin and the quinocyanine pigment is dispersed in this resin according to the general formula (I).

5. Electrophotographic recording material according to claim 2, characterized in that the The charge generating layer additionally contains an electrically insulating resin and the quinocyanine pigment represented by the general formula (I) is dispersed in this resin.

6. Electrophotographic recording material according to claim 1, characterized in that the photoconductive layer contains a charge-transporting matrix and the quinocyanine pigment according to the general formula (I) is dispersed in this charge-transporting matrix.

so 7. electrophotographic recording material according to claims 4 or 5, characterized in that the electrically insulating resin 5 to 90 wt .-% quinocyanine pigment according to the general Formula (I) contains.

8. Electrophotographic recording material according to claims 6 or 7, characterized in that that the charge transport matrix 5 to 90 wt .-% quinocyanine pigment according to the general

Formula (I) contains.

The invention relates to an electrophotographic recording material according to the preamble of claim I. The electrophotographic recording materials are those with inorganic photoconductors, such as amorphous selenium, selenium alloys, cadmium sulfide and zinc oxide, and those with organic photoconductors, which typically include polyvinyl carbazole and its derivatives known.

Amorphous selenium and selenium alloys have excellent properties in electrophotographic recording materials. However, they have disadvantages in that their production is complicated required for deposition. In addition, the deposited films formed are not flexible. Zinc oxide will used for dispersion type recording materials, being dispersed in a resin. at the mechanical strength of these recording materials is low, so that they are unsuitable for repeated operation in this form.

Polyvinyl carbazole has excellent transparency and excellent film-forming properties and flexibility. However, it has no visible sensitivity by itself. From there for this reason polyvinyl carbazole per se cannot be used in practice have been various Sensitization process developed The spectral sensitization of polyvinyl carbazole with a sensitizing dye however, it does not give satisfactory electrical properties in electrophotographic ones Recording materials, although the spectral sensitivity range in the visible range is expanded. In addition, there are disadvantages due to significant light fatigue. By chemical Sensitization with an electron-accepting compound can produce satisfactory electrophotographic results Recording materials can be obtained from the viewpoint of sensitivity. Some of these recording materials are in practical use, but there are still problems in terms of mechanical strength and service life.

From DE-OS 23 09 893 an electrophotographic recording material is known in which on a electrically conductive support is a photoconductive layer, which is a quinocyanine pigment in dispersed form contains This well-known electrophotographic material can be charged positively or negatively, where in absolute values the difference between the positive potential and the negative potential is 80 to 150 volts

The object of the invention is to provide extremely highly sensitive electrophotographic recording materials To provide which can be used in any of the known electrophotographic processes, which have an electrical sensitivity over the entire range of visible light, and at where the difference between the positive and negative loading potential is as low as possible

This object is achieved by the electrophotographic recording material according to claim 1 solved.

For example, fluorine, chlorine, bromine or iodine are suitable as halogen atoms. X can mean, for example Γ, Br ", Cl", ClO ₄ ", BFJ, R ₃ SOJ, where R _{3 is} an unsubstituted alkyl group with 1 to 4 carbon atoms, such as CH ₃ , C ₂ H ₅ , C ₃ H ₇ and C. _{4 represents} H ₉ , or an unsubstituted or substituted phenyl group.

In the formula (I), examples of substituted alkyl groups for B, the alkyl component of which has 1 to 8 carbon atoms, include -CH ₂ C ₆ H ₅ , -CH ₂ CH ₂ Cl, -CH ₂ CH ₂ OH and -CH ₂ CH ₂ COOCH ₃ . Examples of substituents on the aromatic radicals for B include an unsubstituted alkyl group with 1 to 4 carbon atoms (e.g. CH ₃ , C ₂ H ₅ , C ₃ H ₇ and C ₄ H ₉ ), a halogen atom (e.g. F, Cl, Br, I) , a nitro group or a hydrorylgniPF ^ · Examples of unsubstituted alkyl groups for R, and R ₂ are -CH ₃ , -C ₂ H ₅ , -C ₃ H ₇ , -C4H9, -C ₅ Hn, -C ₆ H] ₃ , -C ₇ H] ₅ and -C ₈ H _n ; Examples of substituted alkyl groups in which the alkyl moiety J has up to 8 carbon atoms include -CH ₂ C ₆ H ₅ , -CH ₂ CH ₂ Cl, -CH ₂ CH ₂ COOH, -CH ₂ CH ₂ CN and -CH ₂ CH ₂ OH.

Suitable substituents in the substituted phenyl groups for R ₃ include one or more alkyl groups, halogen atoms (for example F, Cl, Br, I), hydroxyl groups or amino groups.

For specific examples of quinocyanine pigments, according to the aforementioned general Formula, the structural formula is listed below.

C ₂ H ₅ C ₂ H ₅

!, l'-diethyl ^ -bromoquinocyanine iodide

Pigment (2)

C ₂ H ₅ IJ'-diethyl-10-methylquinocarbocyanine iodide

Pigment (3) AA

10

15th

2Ö

25th 30th 35 40 45 50 55 60 65

C ₃ H ₅

C ₂ H ₅

U'-Diethyl-10-ethylquinocarbocyanine iodide

Pigment (4)

C ₂ H ₅

C ₂ H ₃

ίο 15th 20th

■ ο 30 35 40

: · ■ 45 50 55 60

Ι, Γ-diethyl lO-bromoquinocarbocyanine chloride Pigment (5)

CH ₃ CH ₃

1, r-Dimethyl-10-iodoquinocarbocyanine iodide

Pigment (6)

CH = CH-C = CH-CH

1.l'-diethyl-II-ethylquinodicarbocyanine iodide Pigment (7)

CH = CH-C = CH-CH

C ₂ H ₅

l.r-riathyl-ll-bromoquinodicarbocyanine iodide Pigment (8)

CH = CH-C = CH-CH

CH ₃

1, l'-dimethyl-o.o'-diethoxy-l l-chloroquinodicarbocyanine iodide Pigment (9)

= CH-C = CH-CH ^

C ₂ H

l, r, l "-triethyl-II- (2" -quinolyI) -2,2'-quinodicarbocyanine diiodide

65

pigment (10) Br
I. (11) CH =
I. = C-CH C. V
I. 1 II
C ₂ H ₅ C ₃ H ₅
!, r-diethyl-10-bromo-'M'-quinocarbocyanine-iodide pigment

Cl

CH = CH-C = CH-CH

C ₂ H ₅

IO

IS

20th

25th

!, r-Diethyl-II-chloroM / T-quinodicarbocyanine-para-toluenesulfonate Pigment (12)

C ₂ H ₅ C ₂ H ₅

!, l'-diethyl-10-phenylquinocarbocyanine iodide Pigment (13)

CH = CH-C = CH-CH

C ₂ H ₅

C ₂ H ₅

!, l'-diethyl-II-nitroquinodicarbocyanine perchlorate

Pigment (14)

CN

BF7

C ₂ H

₂ H ₅

30th

40 45 50 55 60

C ₂ H ₅ Ι, Ι'-diethyl-II-cyanoquinodicarbocyanine tetrafluoroborate

According to the invention, the quinocyanine pigments corresponding to the formula (I) can also be used for electrophotographic recording materials with a multilayer structure. This means 65 for electrophotographic recording materials that have a photoconductive layer with a two-layered Structure consisting of a charge-generating layer and a charge-transporting layer Improvement of the charging properties as well as a reduction of the residual potential.

In addition, by incorporating the quinocyanine pigments described in the charge-generating layer and the charge-transporting layer, e.g. B. polyvinyl carbazole, an improvement in mechanical strength.

According to the invention, the quinocyanine pigments according to the general formula (I) are dispersed in a binder. It is not necessary that the pigment particles have a particle size on the order of magnitude the molecular size or close to the molecular size. The particle size (diameter) of the pigment parts is preferably 5 μm or less, in particular 1 μm or less. Before dispersing The pigment is ground in the binder. This grinding can be done according to one of the known methods, for example, using a ball mill. It is not desirable that Grinding pigment to a particle size close to the molecular size, as this reduces the electrophotographic properties. The ground pigment, which has a size of about 5 µm or below is added in an amount of 5 to 90% by weight, preferably 10 to 60% by weight, to a binder and dispersed therein.

The binder per se may or may not be photoconductive. Photoconductive binders (charge-transporting matrices) include photoconductive polymers such as polyvinyl carbazole, polyvinyl carbazole derivatives, polyvinyl naphthalene, polyvinyl anthracene and polyvinyl pyrene. These binders can be used in combination with known dye sensitizers. Suitable dye sensitizers include triphenylmethane dyes such as crystal violet, malachite green, brilliant green; Xanthene dyes such as rhodamine B and rhodamine 6 G; Thiazine dyes such as methylene blue and new methylene blue. Also can chemical sensitizers can be used in combination with it. Examples of chemical sensitizers suitable for use are electron-accepting materials such as trinitrofluorenone, tetranitrofluorenone, dinilrodibenzothiophene dioxide and picric acid. The above dye sensitizers and chemical Sensitizers can of course be used in combination.

As a binder, electrically insulating resins which are not photoconductive can be used. Examples of suitable known insulating resins include polystyrene, polyester, polyvinyl toluene, polyvinyl anisole, Polyfluorostyrene, polyvinyl butyral, polyvinyl acetate, polyvinyl butyl methacrylate, styrene-butadiene copolymers, Polysulfone, styrene-methyl methacrylate copolymers and polycarbonate.

In order to further improve the mechanical strength of the recording material, as well as with the common high molecular weight materials - plasticizers can be used. Suitable plasticizers are chlorinated paraffin, chlorinated biphenyl, phosphate plasticizers or phthalate plasticizers. doer.

The plasticizer can be used in an amount up to about 60% by weight, based on the weight of the binder, can be used to further improve the mechanical strength of the recording material without thereby worsening the sensitivity and the electrical properties.

The binder, which contains the quinocyanine pigment in dispersed form, is applied to an electrically conductive support. Various coating methods are used, such as coating by dipping or spraying or coating using an applicator. Any of these methods can produce satisfactory photoconductive layers. Suitable electrically conductive Supports include metals, papers, high molecular weight films and glass that have been surface treated to make them electrically conductive.

The following examples are intended to explain the invention in detail. Unless otherwise stated, refer to all parts and percentages are based on weight.

example 1

The pigment (2) was placed in a ball mill together with tetrahydrofuran (THF) and milled for 48 hours. The milled pigment (2) was mixed in an amount of 20% by weight with the binder (polyester) dissolved in THF. The mixture was applied to an aluminum plate using an applicator and at 70 ⁰ C for 60 min getrockpeL The thickness of the formed film was on a dry basis about 10 microns. Using an electrostatic paper analyzer, the electrophotographic recording material thus prepared was measured for electrical properties. In the case of positive charging, the exposure amount required to reduce the output potential by half was 3 lux-sec.

Examples 2 to 10

As indicated in Example 1, further electrophotographic recording materials were produced, the pigments (3) to (9), (13) and (14) being used in exchange for the pigment (2) used there became. The electrical properties were determined. The results obtained are in the Table 1 summarized.

Pigmeni 27 44 171 705 3.2 Table 1 (3) 770 5.3 Example no. (4) $ 760 5.8 2 (5) 750 1.5 745 5.0 3 (6) 820 2.5 780 2.9 4th (7) 800 2.7 650 4.2 5 (8th) 790 2.3 735 7.1 6th (9) 815 1.6 600 9.5 7th (13) 690 2.0 705 8.7 8th (14) 785 3.3 9 635 5.0 IO 715 4.5

In the table, V £ and Ki mean the potentials that were induced by charging with a direct current of +50 iiA and -50 μΑ , respectively. The exposure required to reduce the output potential around the envelope (£ Ί / Ο was determined by irradiation with a Woifram lamp with a light of 5 iux; in all cases the thickness of the film formed was about 10 µm.

Example 11

Pigment (7) was placed in a test tube together with steel balls and THF and milled for 12 hours. The milled pigment was mixed with the binder polyester in an amount of 30% by weight, dissolved in THF. The thus obtained mixture was coated using a coater on an aluminum sheet and a film is formed with a thickness of about 10 μπι (on dry basis) and dried at 70 ⁰ min C 60. The electrical properties of the electrophotographic recording material obtained in this way were determined as indicated in Example 1. When charged positively, the exposure required to reduce the output potential by half was 1.5 lux · sec. In addition, the properties required for repeated operation were very satisfactory.

Example 12

Pigmeni (7) was ground as indicated in Example 1 and mixed with a binder in an amount of 60% by weight. An aluminum plate was coated with this mixture and a film with a thickness of about 1 μm was produced. Polyvinyl carbazole was applied to this with the aid of an applicator. After 60 minutes of drying at 7O ⁰ C, the thickness of the film formed was about 12 at. Then, the electric characteristics of the laminated electrophotographic recording material were AjF the same manner as defined in Example 1. In the case of negative charging, the exposure required to reduce the initial potential to half was 1.2 lux-sec.

Example 13

Pigment (3) was ground in the same manner in Example 11 and mixed in an amount of 30% by weight with polyvinyl carbazole dissolved in THF. In addition, 0.05% by weight crystal violet was added. The mixture was applied to an aluminum plate with the aid of an application device and ^{dried at 70 °} C. for 5 hours. When the electrophotographic recording material obtained was positively charged, the exposure required to reduce the initial potential to half was 8 lux · sec.

Example 14

Using pigment (11), in the same manner as in Example 11, an electrophotographic was made Recording material produced The results in determining the electrical properties showed that in the case of positive charging, the exposure required to reduce the output potential was 12 lux-sec by half.

Claims (1)

Patent claims: 1. Electrophotographic recording material, with an electrically conductive support on which a photoconductive layer containing an organic photoconductive material is located, the photoconductive layer containing a quinocyanine pigment in dispersed form, characterized in that that the quinocyanine pigment has the following general formula (I): δϊδ) -Α = ί6ϊδ